The present invention pertains generally to magnetic head assemblies, and specifically to a spring retaining clip for securing the back bar to the other core pieces of the magnetic head, to permit simplified manufacturing and assembly procedures.
Although the preferred embodiment of the invention as disclosed herein is described in terms of a read/write head for magnetic floppy disc memory, it will be understood that the principle of the invention applies equally well to read, write or erase heads, for single or multiple head assemblies, for audio, video, computer memory or other magnetic recording/reproduction applications.
A common design for a magnetic head involves a number of core pieces which are positioned together to define the magnetic core of the head. Often, there may be a pair of core pieces made of ferrite or other common core material which have first ends, hereinafter referred to as the "front" ends which are configured to be positioned adjacent each other to cojointly define the head gap. Means are provided for securing these core pieces together in that position. The other ends, hereinafter referred to as the "back" ends of these core pieces are typically separated from each other and an additional core piece, usually referred to as the back bar, is provided for bridging the back ends of the other two core pieces to complete the magnetic circuit. The coil or coils as the case may be, for the head assembly are placed around one or more of the core pieces prior to assembly of the back bar.
In one of the methods of manufacturing a magnetic head assembly of this general type prior to the development of the present invention, it was necessary to assembly the entire core before placing it in the head housing. Because of the extremely small physical dimensions involved, it would have been very difficult to complete the assembly of the core subassembly after placing it within the confines of the protective housing. Thus, it was necessary to place the coil on one of the core pieces with the wires therefor hanging loose, and to glue the back bar in place. The assemblied core unit was then secured in the head housing and the head face was ground and lapped. Subsequently, the wires for the coil (or coils if more than one head were involved in the assembly) were connected to terminal posts, a grounding wire for the core was secured, and a potting material was then poured into the housing.
The above manufacturing procedure was subject to the likelihood of the damage to the fragile core assembly, or breakage to the fragile lead wires. Also, it has been found that the layer of epoxy between the back ends of the core pieces and the back bar prevented intimate contact therewith, resulting in back gaps in the magnetic circuit, which tended to degrade performance. Further, these back gaps were of non-uniform thickness from one unit to the next, resulting in tolerance problems in the performance of the head.
The present invention overcomes these and other problems by providing a spring retaining clip to hold the back bar in place on the back ends of the core pieces. This permits the core subassembly to be positioned within the protective housing, before installation of the coil, thus minimizing danger of damage to the core or wires. After the core is positioned and secured in the housing, in which process the clean back ends of the core pieces can be used as a positioning reference, the face of the head is ground and lapped, and the coil and back bar can be installed. Finally, the electrical connections to the coil or coils can be made, and a grounding connection for the core assembly can be made by a wire attached to the clip.
In the preferred embodiment, the back bar is adhesively secured by epoxy to a surface member of the spring retaining clip, and a ground wire for the core can be soldered to the clip. This permits the back bar to be installed by simply pushing the clip down over the projecting back ends of the core pieces, following which the assembly can be potted.